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hub.c

/*
 * USB hub driver.
 *
 * (C) Copyright 1999 Linus Torvalds
 * (C) Copyright 1999 Johannes Erdfelt
 * (C) Copyright 1999 Gregory P. Smith
 * (C) Copyright 2001 Brad Hards (bhards@bigpond.net.au)
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/ioctl.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/kthread.h>
#include <linux/mutex.h>

#include <asm/semaphore.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>

#include "usb.h"
#include "hcd.h"
#include "hub.h"

/* Protect struct usb_device->state and ->children members
 * Note: Both are also protected by ->dev.sem, except that ->state can
 * change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
static DEFINE_SPINLOCK(device_state_lock);

/* khubd's worklist and its lock */
static DEFINE_SPINLOCK(hub_event_lock);
static LIST_HEAD(hub_event_list);   /* List of hubs needing servicing */

/* Wakes up khubd */
static DECLARE_WAIT_QUEUE_HEAD(khubd_wait);

static struct task_struct *khubd_task;

/* cycle leds on hubs that aren't blinking for attention */
static int blinkenlights = 0;
module_param (blinkenlights, bool, S_IRUGO);
MODULE_PARM_DESC (blinkenlights, "true to cycle leds on hubs");

/*
 * As of 2.6.10 we introduce a new USB device initialization scheme which
 * closely resembles the way Windows works.  Hopefully it will be compatible
 * with a wider range of devices than the old scheme.  However some previously
 * working devices may start giving rise to "device not accepting address"
 * errors; if that happens the user can try the old scheme by adjusting the
 * following module parameters.
 *
 * For maximum flexibility there are two boolean parameters to control the
 * hub driver's behavior.  On the first initialization attempt, if the
 * "old_scheme_first" parameter is set then the old scheme will be used,
 * otherwise the new scheme is used.  If that fails and "use_both_schemes"
 * is set, then the driver will make another attempt, using the other scheme.
 */
static int old_scheme_first = 0;
module_param(old_scheme_first, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(old_scheme_first,
             "start with the old device initialization scheme");

static int use_both_schemes = 1;
module_param(use_both_schemes, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(use_both_schemes,
            "try the other device initialization scheme if the "
            "first one fails");


#ifdef      DEBUG
static inline char *portspeed (int portstatus)
{
      if (portstatus & (1 << USB_PORT_FEAT_HIGHSPEED))
            return "480 Mb/s";
      else if (portstatus & (1 << USB_PORT_FEAT_LOWSPEED))
            return "1.5 Mb/s";
      else
            return "12 Mb/s";
}
#endif

/* Note that hdev or one of its children must be locked! */
static inline struct usb_hub *hdev_to_hub(struct usb_device *hdev)
{
      return usb_get_intfdata(hdev->actconfig->interface[0]);
}

/* USB 2.0 spec Section 11.24.4.5 */
static int get_hub_descriptor(struct usb_device *hdev, void *data, int size)
{
      int i, ret;

      for (i = 0; i < 3; i++) {
            ret = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                  USB_REQ_GET_DESCRIPTOR, USB_DIR_IN | USB_RT_HUB,
                  USB_DT_HUB << 8, 0, data, size,
                  USB_CTRL_GET_TIMEOUT);
            if (ret >= (USB_DT_HUB_NONVAR_SIZE + 2))
                  return ret;
      }
      return -EINVAL;
}

/*
 * USB 2.0 spec Section 11.24.2.1
 */
static int clear_hub_feature(struct usb_device *hdev, int feature)
{
      return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
            USB_REQ_CLEAR_FEATURE, USB_RT_HUB, feature, 0, NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.2
 */
static int clear_port_feature(struct usb_device *hdev, int port1, int feature)
{
      return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
            USB_REQ_CLEAR_FEATURE, USB_RT_PORT, feature, port1,
            NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.13
 */
static int set_port_feature(struct usb_device *hdev, int port1, int feature)
{
      return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
            USB_REQ_SET_FEATURE, USB_RT_PORT, feature, port1,
            NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.7.1.10 and table 11-7
 * for info about using port indicators
 */
static void set_port_led(
      struct usb_hub *hub,
      int port1,
      int selector
)
{
      int status = set_port_feature(hub->hdev, (selector << 8) | port1,
                  USB_PORT_FEAT_INDICATOR);
      if (status < 0)
            dev_dbg (hub->intfdev,
                  "port %d indicator %s status %d\n",
                  port1,
                  ({ char *s; switch (selector) {
                  case HUB_LED_AMBER: s = "amber"; break;
                  case HUB_LED_GREEN: s = "green"; break;
                  case HUB_LED_OFF: s = "off"; break;
                  case HUB_LED_AUTO: s = "auto"; break;
                  default: s = "??"; break;
                  }; s; }),
                  status);
}

#define     LED_CYCLE_PERIOD  ((2*HZ)/3)

static void led_work (void *__hub)
{
      struct usb_hub          *hub = __hub;
      struct usb_device *hdev = hub->hdev;
      unsigned          i;
      unsigned          changed = 0;
      int               cursor = -1;

      if (hdev->state != USB_STATE_CONFIGURED || hub->quiescing)
            return;

      for (i = 0; i < hub->descriptor->bNbrPorts; i++) {
            unsigned    selector, mode;

            /* 30%-50% duty cycle */

            switch (hub->indicator[i]) {
            /* cycle marker */
            case INDICATOR_CYCLE:
                  cursor = i;
                  selector = HUB_LED_AUTO;
                  mode = INDICATOR_AUTO;
                  break;
            /* blinking green = sw attention */
            case INDICATOR_GREEN_BLINK:
                  selector = HUB_LED_GREEN;
                  mode = INDICATOR_GREEN_BLINK_OFF;
                  break;
            case INDICATOR_GREEN_BLINK_OFF:
                  selector = HUB_LED_OFF;
                  mode = INDICATOR_GREEN_BLINK;
                  break;
            /* blinking amber = hw attention */
            case INDICATOR_AMBER_BLINK:
                  selector = HUB_LED_AMBER;
                  mode = INDICATOR_AMBER_BLINK_OFF;
                  break;
            case INDICATOR_AMBER_BLINK_OFF:
                  selector = HUB_LED_OFF;
                  mode = INDICATOR_AMBER_BLINK;
                  break;
            /* blink green/amber = reserved */
            case INDICATOR_ALT_BLINK:
                  selector = HUB_LED_GREEN;
                  mode = INDICATOR_ALT_BLINK_OFF;
                  break;
            case INDICATOR_ALT_BLINK_OFF:
                  selector = HUB_LED_AMBER;
                  mode = INDICATOR_ALT_BLINK;
                  break;
            default:
                  continue;
            }
            if (selector != HUB_LED_AUTO)
                  changed = 1;
            set_port_led(hub, i + 1, selector);
            hub->indicator[i] = mode;
      }
      if (!changed && blinkenlights) {
            cursor++;
            cursor %= hub->descriptor->bNbrPorts;
            set_port_led(hub, cursor + 1, HUB_LED_GREEN);
            hub->indicator[cursor] = INDICATOR_CYCLE;
            changed++;
      }
      if (changed)
            schedule_delayed_work(&hub->leds, LED_CYCLE_PERIOD);
}

/* use a short timeout for hub/port status fetches */
#define     USB_STS_TIMEOUT         1000
#define     USB_STS_RETRIES         5

/*
 * USB 2.0 spec Section 11.24.2.6
 */
static int get_hub_status(struct usb_device *hdev,
            struct usb_hub_status *data)
{
      int i, status = -ETIMEDOUT;

      for (i = 0; i < USB_STS_RETRIES && status == -ETIMEDOUT; i++) {
            status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                  USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_HUB, 0, 0,
                  data, sizeof(*data), USB_STS_TIMEOUT);
      }
      return status;
}

/*
 * USB 2.0 spec Section 11.24.2.7
 */
static int get_port_status(struct usb_device *hdev, int port1,
            struct usb_port_status *data)
{
      int i, status = -ETIMEDOUT;

      for (i = 0; i < USB_STS_RETRIES && status == -ETIMEDOUT; i++) {
            status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                  USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_PORT, 0, port1,
                  data, sizeof(*data), USB_STS_TIMEOUT);
      }
      return status;
}

static void kick_khubd(struct usb_hub *hub)
{
      unsigned long     flags;

      spin_lock_irqsave(&hub_event_lock, flags);
      if (list_empty(&hub->event_list)) {
            list_add_tail(&hub->event_list, &hub_event_list);
            wake_up(&khubd_wait);
      }
      spin_unlock_irqrestore(&hub_event_lock, flags);
}

void usb_kick_khubd(struct usb_device *hdev)
{
      kick_khubd(hdev_to_hub(hdev));
}


/* completion function, fires on port status changes and various faults */
static void hub_irq(struct urb *urb, struct pt_regs *regs)
{
      struct usb_hub *hub = (struct usb_hub *)urb->context;
      int status;
      int i;
      unsigned long bits;

      switch (urb->status) {
      case -ENOENT:           /* synchronous unlink */
      case -ECONNRESET: /* async unlink */
      case -ESHUTDOWN:  /* hardware going away */
            return;

      default:          /* presumably an error */
            /* Cause a hub reset after 10 consecutive errors */
            dev_dbg (hub->intfdev, "transfer --> %d\n", urb->status);
            if ((++hub->nerrors < 10) || hub->error)
                  goto resubmit;
            hub->error = urb->status;
            /* FALL THROUGH */
      
      /* let khubd handle things */
      case 0:                 /* we got data:  port status changed */
            bits = 0;
            for (i = 0; i < urb->actual_length; ++i)
                  bits |= ((unsigned long) ((*hub->buffer)[i]))
                              << (i*8);
            hub->event_bits[0] = bits;
            break;
      }

      hub->nerrors = 0;

      /* Something happened, let khubd figure it out */
      kick_khubd(hub);

resubmit:
      if (hub->quiescing)
            return;

      if ((status = usb_submit_urb (hub->urb, GFP_ATOMIC)) != 0
                  && status != -ENODEV && status != -EPERM)
            dev_err (hub->intfdev, "resubmit --> %d\n", status);
}

/* USB 2.0 spec Section 11.24.2.3 */
static inline int
hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt)
{
      return usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                         HUB_CLEAR_TT_BUFFER, USB_RT_PORT, devinfo,
                         tt, NULL, 0, 1000);
}

/*
 * enumeration blocks khubd for a long time. we use keventd instead, since
 * long blocking there is the exception, not the rule.  accordingly, HCDs
 * talking to TTs must queue control transfers (not just bulk and iso), so
 * both can talk to the same hub concurrently.
 */
static void hub_tt_kevent (void *arg)
{
      struct usb_hub          *hub = arg;
      unsigned long           flags;

      spin_lock_irqsave (&hub->tt.lock, flags);
      while (!list_empty (&hub->tt.clear_list)) {
            struct list_head  *temp;
            struct usb_tt_clear     *clear;
            struct usb_device *hdev = hub->hdev;
            int               status;

            temp = hub->tt.clear_list.next;
            clear = list_entry (temp, struct usb_tt_clear, clear_list);
            list_del (&clear->clear_list);

            /* drop lock so HCD can concurrently report other TT errors */
            spin_unlock_irqrestore (&hub->tt.lock, flags);
            status = hub_clear_tt_buffer (hdev, clear->devinfo, clear->tt);
            spin_lock_irqsave (&hub->tt.lock, flags);

            if (status)
                  dev_err (&hdev->dev,
                        "clear tt %d (%04x) error %d\n",
                        clear->tt, clear->devinfo, status);
            kfree(clear);
      }
      spin_unlock_irqrestore (&hub->tt.lock, flags);
}

/**
 * usb_hub_tt_clear_buffer - clear control/bulk TT state in high speed hub
 * @udev: the device whose split transaction failed
 * @pipe: identifies the endpoint of the failed transaction
 *
 * High speed HCDs use this to tell the hub driver that some split control or
 * bulk transaction failed in a way that requires clearing internal state of
 * a transaction translator.  This is normally detected (and reported) from
 * interrupt context.
 *
 * It may not be possible for that hub to handle additional full (or low)
 * speed transactions until that state is fully cleared out.
 */
void usb_hub_tt_clear_buffer (struct usb_device *udev, int pipe)
{
      struct usb_tt           *tt = udev->tt;
      unsigned long           flags;
      struct usb_tt_clear     *clear;

      /* we've got to cope with an arbitrary number of pending TT clears,
       * since each TT has "at least two" buffers that can need it (and
       * there can be many TTs per hub).  even if they're uncommon.
       */
      if ((clear = kmalloc (sizeof *clear, SLAB_ATOMIC)) == NULL) {
            dev_err (&udev->dev, "can't save CLEAR_TT_BUFFER state\n");
            /* FIXME recover somehow ... RESET_TT? */
            return;
      }

      /* info that CLEAR_TT_BUFFER needs */
      clear->tt = tt->multi ? udev->ttport : 1;
      clear->devinfo = usb_pipeendpoint (pipe);
      clear->devinfo |= udev->devnum << 4;
      clear->devinfo |= usb_pipecontrol (pipe)
                  ? (USB_ENDPOINT_XFER_CONTROL << 11)
                  : (USB_ENDPOINT_XFER_BULK << 11);
      if (usb_pipein (pipe))
            clear->devinfo |= 1 << 15;
      
      /* tell keventd to clear state for this TT */
      spin_lock_irqsave (&tt->lock, flags);
      list_add_tail (&clear->clear_list, &tt->clear_list);
      schedule_work (&tt->kevent);
      spin_unlock_irqrestore (&tt->lock, flags);
}

static void hub_power_on(struct usb_hub *hub)
{
      int port1;
      unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2;
      u16 wHubCharacteristics =
                  le16_to_cpu(hub->descriptor->wHubCharacteristics);

      /* Enable power on each port.  Some hubs have reserved values
       * of LPSM (> 2) in their descriptors, even though they are
       * USB 2.0 hubs.  Some hubs do not implement port-power switching
       * but only emulate it.  In all cases, the ports won't work
       * unless we send these messages to the hub.
       */
      if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2)
            dev_dbg(hub->intfdev, "enabling power on all ports\n");
      else
            dev_dbg(hub->intfdev, "trying to enable port power on "
                        "non-switchable hub\n");
      for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
            set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);

      /* Wait at least 100 msec for power to become stable */
      msleep(max(pgood_delay, (unsigned) 100));
}

static inline void __hub_quiesce(struct usb_hub *hub)
{
      /* (nonblocking) khubd and related activity won't re-trigger */
      hub->quiescing = 1;
      hub->activating = 0;
      hub->resume_root_hub = 0;
}

static void hub_quiesce(struct usb_hub *hub)
{
      /* (blocking) stop khubd and related activity */
      __hub_quiesce(hub);
      usb_kill_urb(hub->urb);
      if (hub->has_indicators)
            cancel_delayed_work(&hub->leds);
      if (hub->has_indicators || hub->tt.hub)
            flush_scheduled_work();
}

static void hub_activate(struct usb_hub *hub)
{
      int   status;

      hub->quiescing = 0;
      hub->activating = 1;
      hub->resume_root_hub = 0;
      status = usb_submit_urb(hub->urb, GFP_NOIO);
      if (status < 0)
            dev_err(hub->intfdev, "activate --> %d\n", status);
      if (hub->has_indicators && blinkenlights)
            schedule_delayed_work(&hub->leds, LED_CYCLE_PERIOD);

      /* scan all ports ASAP */
      kick_khubd(hub);
}

static int hub_hub_status(struct usb_hub *hub,
            u16 *status, u16 *change)
{
      int ret;

      ret = get_hub_status(hub->hdev, &hub->status->hub);
      if (ret < 0)
            dev_err (hub->intfdev,
                  "%s failed (err = %d)\n", __FUNCTION__, ret);
      else {
            *status = le16_to_cpu(hub->status->hub.wHubStatus);
            *change = le16_to_cpu(hub->status->hub.wHubChange); 
            ret = 0;
      }
      return ret;
}

static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
{
      struct usb_device *hdev = hub->hdev;
      int ret;

      if (hdev->children[port1-1] && set_state) {
            usb_set_device_state(hdev->children[port1-1],
                        USB_STATE_NOTATTACHED);
      }
      ret = clear_port_feature(hdev, port1, USB_PORT_FEAT_ENABLE);
      if (ret)
            dev_err(hub->intfdev, "cannot disable port %d (err = %d)\n",
                  port1, ret);

      return ret;
}


/* caller has locked the hub device */
static void hub_pre_reset(struct usb_interface *intf)
{
      struct usb_hub *hub = usb_get_intfdata(intf);
      struct usb_device *hdev = hub->hdev;
      int port1;

      for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
            if (hdev->children[port1 - 1]) {
                  usb_disconnect(&hdev->children[port1 - 1]);
                  if (hub->error == 0)
                        hub_port_disable(hub, port1, 0);
            }
      }
      hub_quiesce(hub);
}

/* caller has locked the hub device */
static void hub_post_reset(struct usb_interface *intf)
{
      struct usb_hub *hub = usb_get_intfdata(intf);

      hub_activate(hub);
      hub_power_on(hub);
}


static int hub_configure(struct usb_hub *hub,
      struct usb_endpoint_descriptor *endpoint)
{
      struct usb_device *hdev = hub->hdev;
      struct device *hub_dev = hub->intfdev;
      u16 hubstatus, hubchange;
      u16 wHubCharacteristics;
      unsigned int pipe;
      int maxp, ret;
      char *message;

      hub->buffer = usb_buffer_alloc(hdev, sizeof(*hub->buffer), GFP_KERNEL,
                  &hub->buffer_dma);
      if (!hub->buffer) {
            message = "can't allocate hub irq buffer";
            ret = -ENOMEM;
            goto fail;
      }

      hub->status = kmalloc(sizeof(*hub->status), GFP_KERNEL);
      if (!hub->status) {
            message = "can't kmalloc hub status buffer";
            ret = -ENOMEM;
            goto fail;
      }

      hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
      if (!hub->descriptor) {
            message = "can't kmalloc hub descriptor";
            ret = -ENOMEM;
            goto fail;
      }

      /* Request the entire hub descriptor.
       * hub->descriptor can handle USB_MAXCHILDREN ports,
       * but the hub can/will return fewer bytes here.
       */
      ret = get_hub_descriptor(hdev, hub->descriptor,
                  sizeof(*hub->descriptor));
      if (ret < 0) {
            message = "can't read hub descriptor";
            goto fail;
      } else if (hub->descriptor->bNbrPorts > USB_MAXCHILDREN) {
            message = "hub has too many ports!";
            ret = -ENODEV;
            goto fail;
      }

      hdev->maxchild = hub->descriptor->bNbrPorts;
      dev_info (hub_dev, "%d port%s detected\n", hdev->maxchild,
            (hdev->maxchild == 1) ? "" : "s");

      wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);

      if (wHubCharacteristics & HUB_CHAR_COMPOUND) {
            int   i;
            char  portstr [USB_MAXCHILDREN + 1];

            for (i = 0; i < hdev->maxchild; i++)
                  portstr[i] = hub->descriptor->DeviceRemovable
                            [((i + 1) / 8)] & (1 << ((i + 1) % 8))
                        ? 'F' : 'R';
            portstr[hdev->maxchild] = 0;
            dev_dbg(hub_dev, "compound device; port removable status: %s\n", portstr);
      } else
            dev_dbg(hub_dev, "standalone hub\n");

      switch (wHubCharacteristics & HUB_CHAR_LPSM) {
            case 0x00:
                  dev_dbg(hub_dev, "ganged power switching\n");
                  break;
            case 0x01:
                  dev_dbg(hub_dev, "individual port power switching\n");
                  break;
            case 0x02:
            case 0x03:
                  dev_dbg(hub_dev, "no power switching (usb 1.0)\n");
                  break;
      }

      switch (wHubCharacteristics & HUB_CHAR_OCPM) {
            case 0x00:
                  dev_dbg(hub_dev, "global over-current protection\n");
                  break;
            case 0x08:
                  dev_dbg(hub_dev, "individual port over-current protection\n");
                  break;
            case 0x10:
            case 0x18:
                  dev_dbg(hub_dev, "no over-current protection\n");
                        break;
      }

      spin_lock_init (&hub->tt.lock);
      INIT_LIST_HEAD (&hub->tt.clear_list);
      INIT_WORK (&hub->tt.kevent, hub_tt_kevent, hub);
      switch (hdev->descriptor.bDeviceProtocol) {
            case 0:
                  break;
            case 1:
                  dev_dbg(hub_dev, "Single TT\n");
                  hub->tt.hub = hdev;
                  break;
            case 2:
                  ret = usb_set_interface(hdev, 0, 1);
                  if (ret == 0) {
                        dev_dbg(hub_dev, "TT per port\n");
                        hub->tt.multi = 1;
                  } else
                        dev_err(hub_dev, "Using single TT (err %d)\n",
                              ret);
                  hub->tt.hub = hdev;
                  break;
            default:
                  dev_dbg(hub_dev, "Unrecognized hub protocol %d\n",
                        hdev->descriptor.bDeviceProtocol);
                  break;
      }

      /* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */
      switch (wHubCharacteristics & HUB_CHAR_TTTT) {
            case HUB_TTTT_8_BITS:
                  if (hdev->descriptor.bDeviceProtocol != 0) {
                        hub->tt.think_time = 666;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                    "FS bit times (%d ns)\n",
                              8, hub->tt.think_time);
                  }
                  break;
            case HUB_TTTT_16_BITS:
                  hub->tt.think_time = 666 * 2;
                  dev_dbg(hub_dev, "TT requires at most %d "
                              "FS bit times (%d ns)\n",
                        16, hub->tt.think_time);
                  break;
            case HUB_TTTT_24_BITS:
                  hub->tt.think_time = 666 * 3;
                  dev_dbg(hub_dev, "TT requires at most %d "
                              "FS bit times (%d ns)\n",
                        24, hub->tt.think_time);
                  break;
            case HUB_TTTT_32_BITS:
                  hub->tt.think_time = 666 * 4;
                  dev_dbg(hub_dev, "TT requires at most %d "
                              "FS bit times (%d ns)\n",
                        32, hub->tt.think_time);
                  break;
      }

      /* probe() zeroes hub->indicator[] */
      if (wHubCharacteristics & HUB_CHAR_PORTIND) {
            hub->has_indicators = 1;
            dev_dbg(hub_dev, "Port indicators are supported\n");
      }

      dev_dbg(hub_dev, "power on to power good time: %dms\n",
            hub->descriptor->bPwrOn2PwrGood * 2);

      /* power budgeting mostly matters with bus-powered hubs,
       * and battery-powered root hubs (may provide just 8 mA).
       */
      ret = usb_get_status(hdev, USB_RECIP_DEVICE, 0, &hubstatus);
      if (ret < 2) {
            message = "can't get hub status";
            goto fail;
      }
      le16_to_cpus(&hubstatus);
      if (hdev == hdev->bus->root_hub) {
            if (hdev->bus_mA == 0 || hdev->bus_mA >= 500)
                  hub->mA_per_port = 500;
            else {
                  hub->mA_per_port = hdev->bus_mA;
                  hub->limited_power = 1;
            }
      } else if ((hubstatus & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
            dev_dbg(hub_dev, "hub controller current requirement: %dmA\n",
                  hub->descriptor->bHubContrCurrent);
            hub->limited_power = 1;
            if (hdev->maxchild > 0) {
                  int remaining = hdev->bus_mA -
                              hub->descriptor->bHubContrCurrent;

                  if (remaining < hdev->maxchild * 100)
                        dev_warn(hub_dev,
                              "insufficient power available "
                              "to use all downstream ports\n");
                  hub->mA_per_port = 100;       /* 7.2.1.1 */
            }
      } else {    /* Self-powered external hub */
            /* FIXME: What about battery-powered external hubs that
             * provide less current per port? */
            hub->mA_per_port = 500;
      }
      if (hub->mA_per_port < 500)
            dev_dbg(hub_dev, "%umA bus power budget for each child\n",
                        hub->mA_per_port);

      ret = hub_hub_status(hub, &hubstatus, &hubchange);
      if (ret < 0) {
            message = "can't get hub status";
            goto fail;
      }

      /* local power status reports aren't always correct */
      if (hdev->actconfig->desc.bmAttributes & USB_CONFIG_ATT_SELFPOWER)
            dev_dbg(hub_dev, "local power source is %s\n",
                  (hubstatus & HUB_STATUS_LOCAL_POWER)
                  ? "lost (inactive)" : "good");

      if ((wHubCharacteristics & HUB_CHAR_OCPM) == 0)
            dev_dbg(hub_dev, "%sover-current condition exists\n",
                  (hubstatus & HUB_STATUS_OVERCURRENT) ? "" : "no ");

      /* set up the interrupt endpoint */
      pipe = usb_rcvintpipe(hdev, endpoint->bEndpointAddress);
      maxp = usb_maxpacket(hdev, pipe, usb_pipeout(pipe));

      if (maxp > sizeof(*hub->buffer))
            maxp = sizeof(*hub->buffer);

      hub->urb = usb_alloc_urb(0, GFP_KERNEL);
      if (!hub->urb) {
            message = "couldn't allocate interrupt urb";
            ret = -ENOMEM;
            goto fail;
      }

      usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
            hub, endpoint->bInterval);
      hub->urb->transfer_dma = hub->buffer_dma;
      hub->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

      /* maybe cycle the hub leds */
      if (hub->has_indicators && blinkenlights)
            hub->indicator [0] = INDICATOR_CYCLE;

      hub_power_on(hub);
      hub_activate(hub);
      return 0;

fail:
      dev_err (hub_dev, "config failed, %s (err %d)\n",
                  message, ret);
      /* hub_disconnect() frees urb and descriptor */
      return ret;
}

static unsigned highspeed_hubs;

static void hub_disconnect(struct usb_interface *intf)
{
      struct usb_hub *hub = usb_get_intfdata (intf);
      struct usb_device *hdev;

      /* Disconnect all children and quiesce the hub */
      hub->error = 0;
      hub_pre_reset(intf);

      usb_set_intfdata (intf, NULL);
      hdev = hub->hdev;

      if (hdev->speed == USB_SPEED_HIGH)
            highspeed_hubs--;

      usb_free_urb(hub->urb);
      hub->urb = NULL;

      spin_lock_irq(&hub_event_lock);
      list_del_init(&hub->event_list);
      spin_unlock_irq(&hub_event_lock);

      kfree(hub->descriptor);
      hub->descriptor = NULL;

      kfree(hub->status);
      hub->status = NULL;

      if (hub->buffer) {
            usb_buffer_free(hdev, sizeof(*hub->buffer), hub->buffer,
                        hub->buffer_dma);
            hub->buffer = NULL;
      }

      kfree(hub);
}

static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
      struct usb_host_interface *desc;
      struct usb_endpoint_descriptor *endpoint;
      struct usb_device *hdev;
      struct usb_hub *hub;

      desc = intf->cur_altsetting;
      hdev = interface_to_usbdev(intf);

#ifdef      CONFIG_USB_OTG_BLACKLIST_HUB
      if (hdev->parent) {
            dev_warn(&intf->dev, "ignoring external hub\n");
            return -ENODEV;
      }
#endif

      /* Some hubs have a subclass of 1, which AFAICT according to the */
      /*  specs is not defined, but it works */
      if ((desc->desc.bInterfaceSubClass != 0) &&
          (desc->desc.bInterfaceSubClass != 1)) {
descriptor_error:
            dev_err (&intf->dev, "bad descriptor, ignoring hub\n");
            return -EIO;
      }

      /* Multiple endpoints? What kind of mutant ninja-hub is this? */
      if (desc->desc.bNumEndpoints != 1)
            goto descriptor_error;

      endpoint = &desc->endpoint[0].desc;

      /* Output endpoint? Curiouser and curiouser.. */
      if (!(endpoint->bEndpointAddress & USB_DIR_IN))
            goto descriptor_error;

      /* If it's not an interrupt endpoint, we'd better punt! */
      if ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
                  != USB_ENDPOINT_XFER_INT)
            goto descriptor_error;

      /* We found a hub */
      dev_info (&intf->dev, "USB hub found\n");

      hub = kzalloc(sizeof(*hub), GFP_KERNEL);
      if (!hub) {
            dev_dbg (&intf->dev, "couldn't kmalloc hub struct\n");
            return -ENOMEM;
      }

      INIT_LIST_HEAD(&hub->event_list);
      hub->intfdev = &intf->dev;
      hub->hdev = hdev;
      INIT_WORK(&hub->leds, led_work, hub);

      usb_set_intfdata (intf, hub);

      if (hdev->speed == USB_SPEED_HIGH)
            highspeed_hubs++;

      if (hub_configure(hub, endpoint) >= 0)
            return 0;

      hub_disconnect (intf);
      return -ENODEV;
}

static int
hub_ioctl(struct usb_interface *intf, unsigned int code, void *user_data)
{
      struct usb_device *hdev = interface_to_usbdev (intf);

      /* assert ifno == 0 (part of hub spec) */
      switch (code) {
      case USBDEVFS_HUB_PORTINFO: {
            struct usbdevfs_hub_portinfo *info = user_data;
            int i;

            spin_lock_irq(&device_state_lock);
            if (hdev->devnum <= 0)
                  info->nports = 0;
            else {
                  info->nports = hdev->maxchild;
                  for (i = 0; i < info->nports; i++) {
                        if (hdev->children[i] == NULL)
                              info->port[i] = 0;
                        else
                              info->port[i] =
                                    hdev->children[i]->devnum;
                  }
            }
            spin_unlock_irq(&device_state_lock);

            return info->nports + 1;
            }

      default:
            return -ENOSYS;
      }
}


/* grab device/port lock, returning index of that port (zero based).
 * protects the upstream link used by this device from concurrent
 * tree operations like suspend, resume, reset, and disconnect, which
 * apply to everything downstream of a given port.
 */
static int locktree(struct usb_device *udev)
{
      int               t;
      struct usb_device *hdev;

      if (!udev)
            return -ENODEV;

      /* root hub is always the first lock in the series */
      hdev = udev->parent;
      if (!hdev) {
            usb_lock_device(udev);
            return 0;
      }

      /* on the path from root to us, lock everything from
       * top down, dropping parent locks when not needed
       */
      t = locktree(hdev);
      if (t < 0)
            return t;

      /* everything is fail-fast once disconnect
       * processing starts
       */
      if (udev->state == USB_STATE_NOTATTACHED) {
            usb_unlock_device(hdev);
            return -ENODEV;
      }

      /* when everyone grabs locks top->bottom,
       * non-overlapping work may be concurrent
       */
      usb_lock_device(udev);
      usb_unlock_device(hdev);
      return udev->portnum;
}

static void recursively_mark_NOTATTACHED(struct usb_device *udev)
{
      int i;

      for (i = 0; i < udev->maxchild; ++i) {
            if (udev->children[i])
                  recursively_mark_NOTATTACHED(udev->children[i]);
      }
      udev->state = USB_STATE_NOTATTACHED;
}

/**
 * usb_set_device_state - change a device's current state (usbcore, hcds)
 * @udev: pointer to device whose state should be changed
 * @new_state: new state value to be stored
 *
 * udev->state is _not_ fully protected by the device lock.  Although
 * most transitions are made only while holding the lock, the state can
 * can change to USB_STATE_NOTATTACHED at almost any time.  This
 * is so that devices can be marked as disconnected as soon as possible,
 * without having to wait for any semaphores to be released.  As a result,
 * all changes to any device's state must be protected by the
 * device_state_lock spinlock.
 *
 * Once a device has been added to the device tree, all changes to its state
 * should be made using this routine.  The state should _not_ be set directly.
 *
 * If udev->state is already USB_STATE_NOTATTACHED then no change is made.
 * Otherwise udev->state is set to new_state, and if new_state is
 * USB_STATE_NOTATTACHED then all of udev's descendants' states are also set
 * to USB_STATE_NOTATTACHED.
 */
void usb_set_device_state(struct usb_device *udev,
            enum usb_device_state new_state)
{
      unsigned long flags;

      spin_lock_irqsave(&device_state_lock, flags);
      if (udev->state == USB_STATE_NOTATTACHED)
            ;     /* do nothing */
      else if (new_state != USB_STATE_NOTATTACHED) {
            udev->state = new_state;

            /* root hub wakeup capabilities are managed out-of-band
             * and may involve silicon errata ... ignore them here.
             */
            if (udev->parent) {
                  if (new_state == USB_STATE_CONFIGURED)
                        device_init_wakeup(&udev->dev,
                              (udev->actconfig->desc.bmAttributes
                               & USB_CONFIG_ATT_WAKEUP));
                  else if (new_state != USB_STATE_SUSPENDED)
                        device_init_wakeup(&udev->dev, 0);
            }
      } else
            recursively_mark_NOTATTACHED(udev);
      spin_unlock_irqrestore(&device_state_lock, flags);
}


#ifdef CONFIG_PM

/**
 * usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
 * @rhdev: struct usb_device for the root hub
 *
 * The USB host controller driver calls this function when its root hub
 * is resumed and Vbus power has been interrupted or the controller
 * has been reset.  The routine marks all the children of the root hub
 * as NOTATTACHED and marks logical connect-change events on their ports.
 */
void usb_root_hub_lost_power(struct usb_device *rhdev)
{
      struct usb_hub *hub;
      int port1;
      unsigned long flags;

      dev_warn(&rhdev->dev, "root hub lost power or was reset\n");
      spin_lock_irqsave(&device_state_lock, flags);
      hub = hdev_to_hub(rhdev);
      for (port1 = 1; port1 <= rhdev->maxchild; ++port1) {
            if (rhdev->children[port1 - 1]) {
                  recursively_mark_NOTATTACHED(
                              rhdev->children[port1 - 1]);
                  set_bit(port1, hub->change_bits);
            }
      }
      spin_unlock_irqrestore(&device_state_lock, flags);
}
EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);

#endif

static void choose_address(struct usb_device *udev)
{
      int         devnum;
      struct usb_bus    *bus = udev->bus;

      /* If khubd ever becomes multithreaded, this will need a lock */

      /* Try to allocate the next devnum beginning at bus->devnum_next. */
      devnum = find_next_zero_bit(bus->devmap.devicemap, 128,
                  bus->devnum_next);
      if (devnum >= 128)
            devnum = find_next_zero_bit(bus->devmap.devicemap, 128, 1);

      bus->devnum_next = ( devnum >= 127 ? 1 : devnum + 1);

      if (devnum < 128) {
            set_bit(devnum, bus->devmap.devicemap);
            udev->devnum = devnum;
      }
}

static void release_address(struct usb_device *udev)
{
      if (udev->devnum > 0) {
            clear_bit(udev->devnum, udev->bus->devmap.devicemap);
            udev->devnum = -1;
      }
}

/**
 * usb_disconnect - disconnect a device (usbcore-internal)
 * @pdev: pointer to device being disconnected
 * Context: !in_interrupt ()
 *
 * Something got disconnected. Get rid of it and all of its children.
 *
 * If *pdev is a normal device then the parent hub must already be locked.
 * If *pdev is a root hub then this routine will acquire the
 * usb_bus_list_lock on behalf of the caller.
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 */
void usb_disconnect(struct usb_device **pdev)
{
      struct usb_device *udev = *pdev;
      int               i;

      if (!udev) {
            pr_debug ("%s nodev\n", __FUNCTION__);
            return;
      }

      /* mark the device as inactive, so any further urb submissions for
       * this device (and any of its children) will fail immediately.
       * this quiesces everyting except pending urbs.
       */
      usb_set_device_state(udev, USB_STATE_NOTATTACHED);
      dev_info (&udev->dev, "USB disconnect, address %d\n", udev->devnum);

      usb_lock_device(udev);

      /* Free up all the children before we remove this device */
      for (i = 0; i < USB_MAXCHILDREN; i++) {
            if (udev->children[i])
                  usb_disconnect(&udev->children[i]);
      }

      /* deallocate hcd/hardware state ... nuking all pending urbs and
       * cleaning up all state associated with the current configuration
       * so that the hardware is now fully quiesced.
       */
      usb_disable_device(udev, 0);

      usb_notify_remove_device(udev);

      /* Free the device number, remove the /proc/bus/usb entry and
       * the sysfs attributes, and delete the parent's children[]
       * (or root_hub) pointer.
       */
      dev_dbg (&udev->dev, "unregistering device\n");
      release_address(udev);
      usb_remove_sysfs_dev_files(udev);

      /* Avoid races with recursively_mark_NOTATTACHED() */
      spin_lock_irq(&device_state_lock);
      *pdev = NULL;
      spin_unlock_irq(&device_state_lock);

      usb_unlock_device(udev);

      device_unregister(&udev->dev);
}

static inline const char *plural(int n)
{
      return (n == 1 ? "" : "s");
}

static int choose_configuration(struct usb_device *udev)
{
      int i;
      int num_configs;
      int insufficient_power = 0;
      struct usb_host_config *c, *best;

      best = NULL;
      c = udev->config;
      num_configs = udev->descriptor.bNumConfigurations;
      for (i = 0; i < num_configs; (i++, c++)) {
            struct usb_interface_descriptor     *desc = NULL;

            /* It's possible that a config has no interfaces! */
            if (c->desc.bNumInterfaces > 0)
                  desc = &c->intf_cache[0]->altsetting->desc;

            /*
             * HP's USB bus-powered keyboard has only one configuration
             * and it claims to be self-powered; other devices may have
             * similar errors in their descriptors.  If the next test
             * were allowed to execute, such configurations would always
             * be rejected and the devices would not work as expected.
             * In the meantime, we run the risk of selecting a config
             * that requires external power at a time when that power
             * isn't available.  It seems to be the lesser of two evils.
             *
             * Bugzilla #6448 reports a device that appears to crash
             * when it receives a GET_DEVICE_STATUS request!  We don't
             * have any other way to tell whether a device is self-powered,
             * but since we don't use that information anywhere but here,
             * the call has been removed.
             *
             * Maybe the GET_DEVICE_STATUS call and the test below can
             * be reinstated when device firmwares become more reliable.
             * Don't hold your breath.
             */
#if 0
            /* Rule out self-powered configs for a bus-powered device */
            if (bus_powered && (c->desc.bmAttributes &
                              USB_CONFIG_ATT_SELFPOWER))
                  continue;
#endif

            /*
             * The next test may not be as effective as it should be.
             * Some hubs have errors in their descriptor, claiming
             * to be self-powered when they are really bus-powered.
             * We will overestimate the amount of current such hubs
             * make available for each port.
             *
             * This is a fairly benign sort of failure.  It won't
             * cause us to reject configurations that we should have
             * accepted.
             */

            /* Rule out configs that draw too much bus current */
            if (c->desc.bMaxPower * 2 > udev->bus_mA) {
                  insufficient_power++;
                  continue;
            }

            /* If the first config's first interface is COMM/2/0xff
             * (MSFT RNDIS), rule it out unless Linux has host-side
             * RNDIS support. */
            if (i == 0 && desc
                        && desc->bInterfaceClass == USB_CLASS_COMM
                        && desc->bInterfaceSubClass == 2
                        && desc->bInterfaceProtocol == 0xff) {
#ifndef CONFIG_USB_NET_RNDIS_HOST
                  continue;
#else
                  best = c;
#endif
            }

            /* From the remaining configs, choose the first one whose
             * first interface is for a non-vendor-specific class.
             * Reason: Linux is more likely to have a class driver
             * than a vendor-specific driver. */
            else if (udev->descriptor.bDeviceClass !=
                                    USB_CLASS_VENDOR_SPEC &&
                        (!desc || desc->bInterfaceClass !=
                                    USB_CLASS_VENDOR_SPEC)) {
                  best = c;
                  break;
            }

            /* If all the remaining configs are vendor-specific,
             * choose the first one. */
            else if (!best)
                  best = c;
      }

      if (insufficient_power > 0)
            dev_info(&udev->dev, "rejected %d configuration%s "
                  "due to insufficient available bus power\n",
                  insufficient_power, plural(insufficient_power));

      if (best) {
            i = best->desc.bConfigurationValue;
            dev_info(&udev->dev,
                  "configuration #%d chosen from %d choice%s\n",
                  i, num_configs, plural(num_configs));
      } else {
            i = -1;
            dev_warn(&udev->dev,
                  "no configuration chosen from %d choice%s\n",
                  num_configs, plural(num_configs));
      }
      return i;
}

#ifdef DEBUG
static void show_string(struct usb_device *udev, char *id, char *string)
{
      if (!string)
            return;
      dev_printk(KERN_INFO, &udev->dev, "%s: %s\n", id, string);
}

#else
static inline void show_string(struct usb_device *udev, char *id, char *string)
{}
#endif


#ifdef      CONFIG_USB_OTG
#include "otg_whitelist.h"
#endif

/**
 * usb_new_device - perform initial device setup (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is called with devices which have been enumerated, but not yet
 * configured.  The device descriptor is available, but not descriptors
 * for any device configuration.  The caller must have locked either
 * the parent hub (if udev is a normal device) or else the
 * usb_bus_list_lock (if udev is a root hub).  The parent's pointer to
 * udev has already been installed, but udev is not yet visible through
 * sysfs or other filesystem code.
 *
 * Returns 0 for success (device is configured and listed, with its
 * interfaces, in sysfs); else a negative errno value.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Only the hub driver or root-hub registrar should ever call this.
 */
int usb_new_device(struct usb_device *udev)
{
      int err;
      int c;

      err = usb_get_configuration(udev);
      if (err < 0) {
            dev_err(&udev->dev, "can't read configurations, error %d\n",
                  err);
            goto fail;
      }

      /* read the standard strings and cache them if present */
      udev->product = usb_cache_string(udev, udev->descriptor.iProduct);
      udev->manufacturer = usb_cache_string(udev,
                  udev->descriptor.iManufacturer);
      udev->serial = usb_cache_string(udev, udev->descriptor.iSerialNumber);

      /* Tell the world! */
      dev_dbg(&udev->dev, "new device strings: Mfr=%d, Product=%d, "
                  "SerialNumber=%d\n",
                  udev->descriptor.iManufacturer,
                  udev->descriptor.iProduct,
                  udev->descriptor.iSerialNumber);
      show_string(udev, "Product", udev->product);
      show_string(udev, "Manufacturer", udev->manufacturer);
      show_string(udev, "SerialNumber", udev->serial);

#ifdef      CONFIG_USB_OTG
      /*
       * OTG-aware devices on OTG-capable root hubs may be able to use SRP,
       * to wake us after we've powered off VBUS; and HNP, switching roles
       * "host" to "peripheral".  The OTG descriptor helps figure this out.
       */
      if (!udev->bus->is_b_host
                  && udev->config
                  && udev->parent == udev->bus->root_hub) {
            struct usb_otg_descriptor     *desc = 0;
            struct usb_bus                *bus = udev->bus;

            /* descriptor may appear anywhere in config */
            if (__usb_get_extra_descriptor (udev->rawdescriptors[0],
                              le16_to_cpu(udev->config[0].desc.wTotalLength),
                              USB_DT_OTG, (void **) &desc) == 0) {
                  if (desc->bmAttributes & USB_OTG_HNP) {
                        unsigned          port1 = udev->portnum;
                        struct usb_device *root = udev->parent;
                        
                        dev_info(&udev->dev,
                              "Dual-Role OTG device on %sHNP port\n",
                              (port1 == bus->otg_port)
                                    ? "" : "non-");

                        /* enable HNP before suspend, it's simpler */
                        if (port1 == bus->otg_port)
                              bus->b_hnp_enable = 1;
                        err = usb_control_msg(udev,
                              usb_sndctrlpipe(udev, 0),
                              USB_REQ_SET_FEATURE, 0,
                              bus->b_hnp_enable
                                    ? USB_DEVICE_B_HNP_ENABLE
                                    : USB_DEVICE_A_ALT_HNP_SUPPORT,
                              0, NULL, 0, USB_CTRL_SET_TIMEOUT);
                        if (err < 0) {
                              /* OTG MESSAGE: report errors here,
                               * customize to match your product.
                               */
                              dev_info(&udev->dev,
                                    "can't set HNP mode; %d\n",
                                    err);
                              bus->b_hnp_enable = 0;
                        }
                  }
            }
      }

      if (!is_targeted(udev)) {

            /* Maybe it can talk to us, though we can't talk to it.
             * (Includes HNP test device.)
             */
            if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
                  static int __usb_suspend_device(struct usb_device *,
                                    int port1);
                  err = __usb_suspend_device(udev, udev->bus->otg_port);
                  if (err < 0)
                        dev_dbg(&udev->dev, "HNP fail, %d\n", err);
            }
            err = -ENODEV;
            goto fail;
      }
#endif

      /* put device-specific files into sysfs */
      err = device_add (&udev->dev);
      if (err) {
            dev_err(&udev->dev, "can't device_add, error %d\n", err);
            goto fail;
      }
      usb_create_sysfs_dev_files (udev);

      usb_lock_device(udev);

      /* choose and set the configuration. that registers the interfaces
       * with the driver core, and lets usb device drivers bind to them.
       */
      c = choose_configuration(udev);
      if (c >= 0) {
            err = usb_set_configuration(udev, c);
            if (err) {
                  dev_err(&udev->dev, "can't set config #%d, error %d\n",
                              c, err);
                  /* This need not be fatal.  The user can try to
                   * set other configurations. */
            }
      }

      /* USB device state == configured ... usable */
      usb_notify_add_device(udev);

      usb_unlock_device(udev);

      return 0;

fail:
      usb_set_device_state(udev, USB_STATE_NOTATTACHED);
      return err;
}


static int hub_port_status(struct usb_hub *hub, int port1,
                         u16 *status, u16 *change)
{
      int ret;

      ret = get_port_status(hub->hdev, port1, &hub->status->port);
      if (ret < 0)
            dev_err (hub->intfdev,
                  "%s failed (err = %d)\n", __FUNCTION__, ret);
      else {
            *status = le16_to_cpu(hub->status->port.wPortStatus);
            *change = le16_to_cpu(hub->status->port.wPortChange); 
            ret = 0;
      }
      return ret;
}

#define PORT_RESET_TRIES      5
#define SET_ADDRESS_TRIES     2
#define GET_DESCRIPTOR_TRIES  2
#define SET_CONFIG_TRIES      (2 * (use_both_schemes + 1))
#define USE_NEW_SCHEME(i)     ((i) / 2 == old_scheme_first)

#define HUB_ROOT_RESET_TIME   50    /* times are in msec */
#define HUB_SHORT_RESET_TIME  10
#define HUB_LONG_RESET_TIME   200
#define HUB_RESET_TIMEOUT     500

static int hub_port_wait_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, unsigned int delay)
{
      int delay_time, ret;
      u16 portstatus;
      u16 portchange;

      for (delay_time = 0;
                  delay_time < HUB_RESET_TIMEOUT;
                  delay_time += delay) {
            /* wait to give the device a chance to reset */
            msleep(delay);

            /* read and decode port status */
            ret = hub_port_status(hub, port1, &portstatus, &portchange);
            if (ret < 0)
                  return ret;

            /* Device went away? */
            if (!(portstatus & USB_PORT_STAT_CONNECTION))
                  return -ENOTCONN;

            /* bomb out completely if something weird happened */
            if ((portchange & USB_PORT_STAT_C_CONNECTION))
                  return -EINVAL;

            /* if we`ve finished resetting, then break out of the loop */
            if (!(portstatus & USB_PORT_STAT_RESET) &&
                (portstatus & USB_PORT_STAT_ENABLE)) {
                  if (portstatus & USB_PORT_STAT_HIGH_SPEED)
                        udev->speed = USB_SPEED_HIGH;
                  else if (portstatus & USB_PORT_STAT_LOW_SPEED)
                        udev->speed = USB_SPEED_LOW;
                  else
                        udev->speed = USB_SPEED_FULL;
                  return 0;
            }

            /* switch to the long delay after two short delay failures */
            if (delay_time >= 2 * HUB_SHORT_RESET_TIME)
                  delay = HUB_LONG_RESET_TIME;

            dev_dbg (hub->intfdev,
                  "port %d not reset yet, waiting %dms\n",
                  port1, delay);
      }

      return -EBUSY;
}

static int hub_port_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, unsigned int delay)
{
      int i, status;

      /* Reset the port */
      for (i = 0; i < PORT_RESET_TRIES; i++) {
            status = set_port_feature(hub->hdev,
                        port1, USB_PORT_FEAT_RESET);
            if (status)
                  dev_err(hub->intfdev,
                              "cannot reset port %d (err = %d)\n",
                              port1, status);
            else {
                  status = hub_port_wait_reset(hub, port1, udev, delay);
                  if (status && status != -ENOTCONN)
                        dev_dbg(hub->intfdev,
                                    "port_wait_reset: err = %d\n",
                                    status);
            }

            /* return on disconnect or reset */
            switch (status) {
            case 0:
                  /* TRSTRCY = 10 ms; plus some extra */
                  msleep(10 + 40);
                  /* FALL THROUGH */
            case -ENOTCONN:
            case -ENODEV:
                  clear_port_feature(hub->hdev,
                        port1, USB_PORT_FEAT_C_RESET);
                  /* FIXME need disconnect() for NOTATTACHED device */
                  usb_set_device_state(udev, status
                              ? USB_STATE_NOTATTACHED
                              : USB_STATE_DEFAULT);
                  return status;
            }

            dev_dbg (hub->intfdev,
                  "port %d not enabled, trying reset again...\n",
                  port1);
            delay = HUB_LONG_RESET_TIME;
      }

      dev_err (hub->intfdev,
            "Cannot enable port %i.  Maybe the USB cable is bad?\n",
            port1);

      return status;
}

/*
 * Disable a port and mark a logical connnect-change event, so that some
 * time later khubd will disconnect() any existing usb_device on the port
 * and will re-enumerate if there actually is a device attached.
 */
static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
{
      dev_dbg(hub->intfdev, "logical disconnect on port %d\n", port1);
      hub_port_disable(hub, port1, 1);

      /* FIXME let caller ask to power down the port:
       *  - some devices won't enumerate without a VBUS power cycle
       *  - SRP saves power that way
       *  - ... new call, TBD ...
       * That's easy if this hub can switch power per-port, and
       * khubd reactivates the port later (timer, SRP, etc).
       * Powerdown must be optional, because of reset/DFU.
       */

      set_bit(port1, hub->change_bits);
      kick_khubd(hub);
}


#ifdef      CONFIG_USB_SUSPEND

/*
 * Selective port suspend reduces power; most suspended devices draw
 * less than 500 uA.  It's also used in OTG, along with remote wakeup.
 * All devices below the suspended port are also suspended.
 *
 * Devices leave suspend state when the host wakes them up.  Some devices
 * also support "remote wakeup", where the device can activate the USB
 * tree above them to deliver data, such as a keypress or packet.  In
 * some cases, this wakes the USB host.
 */
static int hub_port_suspend(struct usb_hub *hub, int port1,
            struct usb_device *udev)
{
      int   status;

      // dev_dbg(hub->intfdev, "suspend port %d\n", port1);

      /* enable remote wakeup when appropriate; this lets the device
       * wake up the upstream hub (including maybe the root hub).
       *
       * NOTE:  OTG devices may issue remote wakeup (or SRP) even when
       * we don't explicitly enable it here.
       */
      if (device_may_wakeup(&udev->dev)) {
            status = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
                        USB_DEVICE_REMOTE_WAKEUP, 0,
                        NULL, 0,
                        USB_CTRL_SET_TIMEOUT);
            if (status)
                  dev_dbg(&udev->dev,
                        "won't remote wakeup, status %d\n",
                        status);
      }

      /* see 7.1.7.6 */
      status = set_port_feature(hub->hdev, port1, USB_PORT_FEAT_SUSPEND);
      if (status) {
            dev_dbg(hub->intfdev,
                  "can't suspend port %d, status %d\n",
                  port1, status);
            /* paranoia:  "should not happen" */
            (void) usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE,
                        USB_DEVICE_REMOTE_WAKEUP, 0,
                        NULL, 0,
                        USB_CTRL_SET_TIMEOUT);
      } else {
            /* device has up to 10 msec to fully suspend */
            dev_dbg(&udev->dev, "usb suspend\n");
            usb_set_device_state(udev, USB_STATE_SUSPENDED);
            msleep(10);
      }
      return status;
}

/*
 * Devices on USB hub ports have only one "suspend" state, corresponding
 * to ACPI D2, "may cause the device to lose some context".
 * State transitions include:
 *
 *   - suspend, resume ... when the VBUS power link stays live
 *   - suspend, disconnect ... VBUS lost
 *
 * Once VBUS drop breaks the circuit, the port it's using has to go through
 * normal re-enumeration procedures, starting with enabling VBUS power.
 * Other than re-initializing the hub (plug/unplug, except for root hubs),
 * Linux (2.6) currently has NO mechanisms to initiate that:  no khubd
 * timer, no SRP, no requests through sysfs.
 *
 * If CONFIG_USB_SUSPEND isn't enabled, devices only really suspend when
 * the root hub for their bus goes into global suspend ... so we don't
 * (falsely) update the device power state to say it suspended.
 */
static int __usb_suspend_device (struct usb_device *udev, int port1)
{
      int   status = 0;

      /* caller owns the udev device lock */
      if (port1 < 0)
            return port1;

      if (udev->state == USB_STATE_SUSPENDED
                  || udev->state == USB_STATE_NOTATTACHED) {
            return 0;
      }

      /* all interfaces must already be suspended */
      if (udev->actconfig) {
            int   i;

            for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                  struct usb_interface    *intf;

                  intf = udev->actconfig->interface[i];
                  if (is_active(intf)) {
                        dev_dbg(&intf->dev, "nyet suspended\n");
                        return -EBUSY;
                  }
            }
      }

      /* we only change a device's upstream USB link.
       * root hubs have no upstream USB link.
       */
      if (udev->parent)
            status = hub_port_suspend(hdev_to_hub(udev->parent), port1,
                        udev);

      if (status == 0)
            udev->dev.power.power_state = PMSG_SUSPEND;
      return status;
}

#endif

/*
 * usb_suspend_device - suspend a usb device
 * @udev: device that's no longer in active use
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * Suspends a USB device that isn't in active use, conserving power.
 * Devices may wake out of a suspend, if anything important happens,
 * using the remote wakeup mechanism.  They may also be taken out of
 * suspend by the host, using usb_resume_device().  It's also routine
 * to disconnect devices while they are suspended.
 *
 * This only affects the USB hardware for a device; its interfaces
 * (and, for hubs, child devices) must already have been suspended.
 *
 * Suspending OTG devices may trigger HNP, if that's been enabled
 * between a pair of dual-role devices.  That will change roles, such
 * as from A-Host to A-Peripheral or from B-Host back to B-Peripheral.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_suspend_device(struct usb_device *udev)
{
#ifdef      CONFIG_USB_SUSPEND
      if (udev->state == USB_STATE_NOTATTACHED)
            return -ENODEV;
      return __usb_suspend_device(udev, udev->portnum);
#else
      /* NOTE:  udev->state unchanged, it's not lying ... */
      udev->dev.power.power_state = PMSG_SUSPEND;
      return 0;
#endif
}

/*
 * If the USB "suspend" state is in use (rather than "global suspend"),
 * many devices will be individually taken out of suspend state using
 * special" resume" signaling.  These routines kick in shortly after
 * hardware resume signaling is finished, either because of selective
 * resume (by host) or remote wakeup (by device) ... now see what changed
 * in the tree that's rooted at this device.
 */
static int finish_device_resume(struct usb_device *udev)
{
      int   status;
      u16   devstatus;

      /* caller owns the udev device lock */
      dev_dbg(&udev->dev, "finish resume\n");

      /* usb ch9 identifies four variants of SUSPENDED, based on what
       * state the device resumes to.  Linux currently won't see the
       * first two on the host side; they'd be inside hub_port_init()
       * during many timeouts, but khubd can't suspend until later.
       */
      usb_set_device_state(udev, udev->actconfig
                  ? USB_STATE_CONFIGURED
                  : USB_STATE_ADDRESS);
      udev->dev.power.power_state = PMSG_ON;

      /* 10.5.4.5 says be sure devices in the tree are still there.
       * For now let's assume the device didn't go crazy on resume,
       * and device drivers will know about any resume quirks.
       */
      status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);
      if (status >= 0)
            status = (status == 2 ? 0 : -ENODEV);

      if (status)
            dev_dbg(&udev->dev,
                  "gone after usb resume? status %d\n",
                  status);
      else if (udev->actconfig) {
            unsigned    i;
            int         (*resume)(struct device *);

            le16_to_cpus(&devstatus);
            if ((devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP))
                        && udev->parent) {
                  status = usb_control_msg(udev,
                              usb_sndctrlpipe(udev, 0),
                              USB_REQ_CLEAR_FEATURE,
                                    USB_RECIP_DEVICE,
                              USB_DEVICE_REMOTE_WAKEUP, 0,
                              NULL, 0,
                              USB_CTRL_SET_TIMEOUT);
                  if (status) {
                        dev_dbg(&udev->dev, "disable remote "
                              "wakeup, status %d\n", status);
                        status = 0;
                  }
            }

            /* resume interface drivers; if this is a hub, it
             * may have a child resume event to deal with soon
             */
            resume = udev->dev.bus->resume;
            for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                  struct device *dev =
                              &udev->actconfig->interface[i]->dev;

                  down(&dev->sem);
                  (void) resume(dev);
                  up(&dev->sem);
            }
            status = 0;

      } else if (udev->devnum <= 0) {
            dev_dbg(&udev->dev, "bogus resume!\n");
            status = -EINVAL;
      }
      return status;
}

#ifdef      CONFIG_USB_SUSPEND

static int
hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
{
      int   status;

      // dev_dbg(hub->intfdev, "resume port %d\n", port1);

      /* see 7.1.7.7; affects power usage, but not budgeting */
      status = clear_port_feature(hub->hdev,
                  port1, USB_PORT_FEAT_SUSPEND);
      if (status) {
            dev_dbg(hub->intfdev,
                  "can't resume port %d, status %d\n",
                  port1, status);
      } else {
            u16         devstatus;
            u16         portchange;

            /* drive resume for at least 20 msec */
            if (udev)
                  dev_dbg(&udev->dev, "RESUME\n");
            msleep(25);

#define LIVE_FLAGS      ( USB_PORT_STAT_POWER \
                  | USB_PORT_STAT_ENABLE \
                  | USB_PORT_STAT_CONNECTION)

            /* Virtual root hubs can trigger on GET_PORT_STATUS to
             * stop resume signaling.  Then finish the resume
             * sequence.
             */
            devstatus = portchange = 0;
            status = hub_port_status(hub, port1,
                        &devstatus, &portchange);
            if (status < 0
                        || (devstatus & LIVE_FLAGS) != LIVE_FLAGS
                        || (devstatus & USB_PORT_STAT_SUSPEND) != 0
                        ) {
                  dev_dbg(hub->intfdev,
                        "port %d status %04x.%04x after resume, %d\n",
                        port1, portchange, devstatus, status);
                  if (status >= 0)
                        status = -ENODEV;
            } else {
                  if (portchange & USB_PORT_STAT_C_SUSPEND)
                        clear_port_feature(hub->hdev, port1,
                                    USB_PORT_FEAT_C_SUSPEND);
                  /* TRSMRCY = 10 msec */
                  msleep(10);
                  if (udev)
                        status = finish_device_resume(udev);
            }
      }
      if (status < 0)
            hub_port_logical_disconnect(hub, port1);

      return status;
}

#endif

/*
 * usb_resume_device - re-activate a suspended usb device
 * @udev: device to re-activate
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * This will re-activate the suspended device, increasing power usage
 * while letting drivers communicate again with its endpoints.
 * USB resume explicitly guarantees that the power session between
 * the host and the device is the same as it was when the device
 * suspended.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_resume_device(struct usb_device *udev)
{
      int   status;

      if (udev->state == USB_STATE_NOTATTACHED)
            return -ENODEV;

      /* selective resume of one downstream hub-to-device port */
      if (udev->parent) {
#ifdef      CONFIG_USB_SUSPEND
            if (udev->state == USB_STATE_SUSPENDED) {
                  // NOTE swsusp may bork us, device state being wrong...
                  // NOTE this fails if parent is also suspended...
                  status = hub_port_resume(hdev_to_hub(udev->parent),
                              udev->portnum, udev);
            } else
#endif
                  status = 0;
      } else
            status = finish_device_resume(udev);
      if (status < 0)
            dev_dbg(&udev->dev, "can't resume, status %d\n",
                  status);

      /* rebind drivers that had no suspend() */
      if (status == 0) {
            usb_unlock_device(udev);
            bus_rescan_devices(&usb_bus_type);
            usb_lock_device(udev);
      }
      return status;
}

static int remote_wakeup(struct usb_device *udev)
{
      int   status = 0;

#ifdef      CONFIG_USB_SUSPEND

      /* don't repeat RESUME sequence if this device
       * was already woken up by some other task
       */
      usb_lock_device(udev);
      if (udev->state == USB_STATE_SUSPENDED) {
            dev_dbg(&udev->dev, "RESUME (wakeup)\n");
            /* TRSMRCY = 10 msec */
            msleep(10);
            status = finish_device_resume(udev);
      }
      usb_unlock_device(udev);
#endif
      return status;
}

static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
{
      struct usb_hub          *hub = usb_get_intfdata (intf);
      struct usb_device *hdev = hub->hdev;
      unsigned          port1;

      /* fail if children aren't already suspended */
      for (port1 = 1; port1 <= hdev->maxchild; port1++) {
            struct usb_device *udev;

            udev = hdev->children [port1-1];
            if (udev && (udev->dev.power.power_state.event
                              == PM_EVENT_ON
#ifdef      CONFIG_USB_SUSPEND
                        || udev->state != USB_STATE_SUSPENDED
#endif
                        )) {
                  dev_dbg(&intf->dev, "port %d nyet suspended\n", port1);
                  return -EBUSY;
            }
      }

      /* "global suspend" of the downstream HC-to-USB interface */
      if (!hdev->parent) {
            struct usb_bus    *bus = hdev->bus;
            if (bus) {
                  int   status = hcd_bus_suspend (bus);

                  if (status != 0) {
                        dev_dbg(&hdev->dev, "'global' suspend %d\n",
                              status);
                        return status;
                  }
            } else
                  return -EOPNOTSUPP;
      }

      /* stop khubd and related activity */
      hub_quiesce(hub);
      return 0;
}

static int hub_resume(struct usb_interface *intf)
{
      struct usb_device *hdev = interface_to_usbdev(intf);
      struct usb_hub          *hub = usb_get_intfdata (intf);
      int               status;

      /* "global resume" of the downstream HC-to-USB interface */
      if (!hdev->parent) {
            struct usb_bus    *bus = hdev->bus;
            if (bus) {
                  status = hcd_bus_resume (bus);
                  if (status) {
                        dev_dbg(&intf->dev, "'global' resume %d\n",
                              status);
                        return status;
                  }
            } else
                  return -EOPNOTSUPP;
            if (status == 0) {
                  /* TRSMRCY = 10 msec */
                  msleep(10);
            }
      }

      hub_activate(hub);

      /* REVISIT:  this recursion probably shouldn't exist.  Remove
       * this code sometime, after retesting with different root and
       * external hubs.
       */
#ifdef      CONFIG_USB_SUSPEND
      {
      unsigned          port1;

      for (port1 = 1; port1 <= hdev->maxchild; port1++) {
            struct usb_device *udev;
            u16               portstat, portchange;

            udev = hdev->children [port1-1];
            status = hub_port_status(hub, port1, &portstat, &portchange);
            if (status == 0) {
                  if (portchange & USB_PORT_STAT_C_SUSPEND) {
                        clear_port_feature(hdev, port1,
                              USB_PORT_FEAT_C_SUSPEND);
                        portchange &= ~USB_PORT_STAT_C_SUSPEND;
                  }

                  /* let khubd handle disconnects etc */
                  if (portchange)
                        continue;
            }

            if (!udev || status < 0)
                  continue;
            usb_lock_device(udev);
            if (portstat & USB_PORT_STAT_SUSPEND)
                  status = hub_port_resume(hub, port1, udev);
            else {
                  status = finish_device_resume(udev);
                  if (status < 0) {
                        dev_dbg(&intf->dev, "resume port %d --> %d\n",
                              port1, status);
                        hub_port_logical_disconnect(hub, port1);
                  }
            }
            usb_unlock_device(udev);
      }
      }
#endif
      return 0;
}

void usb_suspend_root_hub(struct usb_device *hdev)
{
      struct usb_hub *hub = hdev_to_hub(hdev);

      /* This also makes any led blinker stop retriggering.  We're called
       * from irq, so the blinker might still be scheduled.  Caller promises
       * that the root hub status URB will be canceled.
       */
      __hub_quiesce(hub);
      mark_quiesced(to_usb_interface(hub->intfdev));
}

void usb_resume_root_hub(struct usb_device *hdev)
{
      struct usb_hub *hub = hdev_to_hub(hdev);

      hub->resume_root_hub = 1;
      kick_khubd(hub);
}


/* USB 2.0 spec, 7.1.7.3 / fig 7-29:
 *
 * Between connect detection and reset signaling there must be a delay
 * of 100ms at least for debounce and power-settling.  The corresponding
 * timer shall restart whenever the downstream port detects a disconnect.
 * 
 * Apparently there are some bluetooth and irda-dongles and a number of
 * low-speed devices for which this debounce period may last over a second.
 * Not covered by the spec - but easy to deal with.
 *
 * This implementation uses a 1500ms total debounce timeout; if the
 * connection isn't stable by then it returns -ETIMEDOUT.  It checks
 * every 25ms for transient disconnects.  When the port status has been
 * unchanged for 100ms it returns the port status.
 */

#define HUB_DEBOUNCE_TIMEOUT  1500
#define HUB_DEBOUNCE_STEP       25
#define HUB_DEBOUNCE_STABLE    100

static int hub_port_debounce(struct usb_hub *hub, int port1)
{
      int ret;
      int total_time, stable_time = 0;
      u16 portchange, portstatus;
      unsigned connection = 0xffff;

      for (total_time = 0; ; total_time += HUB_DEBOUNCE_STEP) {
            ret = hub_port_status(hub, port1, &portstatus, &portchange);
            if (ret < 0)
                  return ret;

            if (!(portchange & USB_PORT_STAT_C_CONNECTION) &&
                 (portstatus & USB_PORT_STAT_CONNECTION) == connection) {
                  stable_time += HUB_DEBOUNCE_STEP;
                  if (stable_time >= HUB_DEBOUNCE_STABLE)
                        break;
            } else {
                  stable_time = 0;
                  connection = portstatus & USB_PORT_STAT_CONNECTION;
            }

            if (portchange & USB_PORT_STAT_C_CONNECTION) {
                  clear_port_feature(hub->hdev, port1,
                              USB_PORT_FEAT_C_CONNECTION);
            }

            if (total_time >= HUB_DEBOUNCE_TIMEOUT)
                  break;
            msleep(HUB_DEBOUNCE_STEP);
      }

      dev_dbg (hub->intfdev,
            "debounce: port %d: total %dms stable %dms status 0x%x\n",
            port1, total_time, stable_time, portstatus);

      if (stable_time < HUB_DEBOUNCE_STABLE)
            return -ETIMEDOUT;
      return portstatus;
}

static void ep0_reinit(struct usb_device *udev)
{
      usb_disable_endpoint(udev, 0 + USB_DIR_IN);
      usb_disable_endpoint(udev, 0 + USB_DIR_OUT);
      udev->ep_in[0] = udev->ep_out[0] = &udev->ep0;
}

#define usb_sndaddr0pipe()    (PIPE_CONTROL << 30)
#define usb_rcvaddr0pipe()    ((PIPE_CONTROL << 30) | USB_DIR_IN)

static int hub_set_address(struct usb_device *udev)
{
      int retval;

      if (udev->devnum == 0)
            return -EINVAL;
      if (udev->state == USB_STATE_ADDRESS)
            return 0;
      if (udev->state != USB_STATE_DEFAULT)
            return -EINVAL;
      retval = usb_control_msg(udev, usb_sndaddr0pipe(),
            USB_REQ_SET_ADDRESS, 0, udev->devnum, 0,
            NULL, 0, USB_CTRL_SET_TIMEOUT);
      if (retval == 0) {
            usb_set_device_state(udev, USB_STATE_ADDRESS);
            ep0_reinit(udev);
      }
      return retval;
}

/* Reset device, (re)assign address, get device descriptor.
 * Device connection must be stable, no more debouncing needed.
 * Returns device in USB_STATE_ADDRESS, except on error.
 *
 * If this is called for an already-existing device (as part of
 * usb_reset_device), the caller must own the device lock.  For a
 * newly detected device that is not accessible through any global
 * pointers, it's not necessary to lock the device.
 */
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
            int retry_counter)
{
      static DEFINE_MUTEX(usb_address0_mutex);

      struct usb_device *hdev = hub->hdev;
      int               i, j, retval;
      unsigned          delay = HUB_SHORT_RESET_TIME;
      enum usb_device_speed   oldspeed = udev->speed;

      /* root hub ports have a slightly longer reset period
       * (from USB 2.0 spec, section 7.1.7.5)
       */
      if (!hdev->parent) {
            delay = HUB_ROOT_RESET_TIME;
            if (port1 == hdev->bus->otg_port)
                  hdev->bus->b_hnp_enable = 0;
      }

      /* Some low speed devices have problems with the quick delay, so */
      /*  be a bit pessimistic with those devices. RHbug #23670 */
      if (oldspeed == USB_SPEED_LOW)
            delay = HUB_LONG_RESET_TIME;

      mutex_lock(&usb_address0_mutex);

      /* Reset the device; full speed may morph to high speed */
      retval = hub_port_reset(hub, port1, udev, delay);
      if (retval < 0)         /* error or disconnect */
            goto fail;
                        /* success, speed is known */
      retval = -ENODEV;

      if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
            dev_dbg(&udev->dev, "device reset changed speed!\n");
            goto fail;
      }
      oldspeed = udev->speed;
  
      /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
       * it's fixed size except for full speed devices.
       */
      switch (udev->speed) {
      case USB_SPEED_HIGH:          /* fixed at 64 */
            udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
            break;
      case USB_SPEED_FULL:          /* 8, 16, 32, or 64 */
            /* to determine the ep0 maxpacket size, try to read
             * the device descriptor to get bMaxPacketSize0 and
             * then correct our initial guess.
             */
            udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
            break;
      case USB_SPEED_LOW:           /* fixed at 8 */
            udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(8);
            break;
      default:
            goto fail;
      }
 
      dev_info (&udev->dev,
                  "%s %s speed USB device using %s and address %d\n",
                  (udev->config) ? "reset" : "new",
                  ({ char *speed; switch (udev->speed) {
                  case USB_SPEED_LOW:     speed = "low";    break;
                  case USB_SPEED_FULL:    speed = "full";   break;
                  case USB_SPEED_HIGH:    speed = "high";   break;
                  default:          speed = "?";      break;
                  }; speed;}),
                  udev->bus->controller->driver->name,
                  udev->devnum);

      /* Set up TT records, if needed  */
      if (hdev->tt) {
            udev->tt = hdev->tt;
            udev->ttport = hdev->ttport;
      } else if (udev->speed != USB_SPEED_HIGH
                  && hdev->speed == USB_SPEED_HIGH) {
            udev->tt = &hub->tt;
            udev->ttport = port1;
      }
 
      /* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
       * Because device hardware and firmware is sometimes buggy in
       * this area, and this is how Linux has done it for ages.
       * Change it cautiously.
       *
       * NOTE:  If USE_NEW_SCHEME() is true we will start by issuing
       * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
       * so it may help with some non-standards-compliant devices.
       * Otherwise we start with SET_ADDRESS and then try to read the
       * first 8 bytes of the device descriptor to get the ep0 maxpacket
       * value.
       */
      for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
            if (USE_NEW_SCHEME(retry_counter)) {
                  struct usb_device_descriptor *buf;
                  int r = 0;

#define GET_DESCRIPTOR_BUFSIZE      64
                  buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
                  if (!buf) {
                        retval = -ENOMEM;
                        continue;
                  }

                  /* Use a short timeout the first time through,
                   * so that recalcitrant full-speed devices with
                   * 8- or 16-byte ep0-maxpackets won't slow things
                   * down tremendously by NAKing the unexpectedly
                   * early status stage.  Also, retry on all errors;
                   * some devices are flakey.
                   */
                  for (j = 0; j < 3; ++j) {
                        buf->bMaxPacketSize0 = 0;
                        r = usb_control_msg(udev, usb_rcvaddr0pipe(),
                              USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
                              USB_DT_DEVICE << 8, 0,
                              buf, GET_DESCRIPTOR_BUFSIZE,
                              (i ? USB_CTRL_GET_TIMEOUT : 1000));
                        switch (buf->bMaxPacketSize0) {
                        case 8: case 16: case 32: case 64:
                              if (buf->bDescriptorType ==
                                          USB_DT_DEVICE) {
                                    r = 0;
                                    break;
                              }
                              /* FALL THROUGH */
                        default:
                              if (r == 0)
                                    r = -EPROTO;
                              break;
                        }
                        if (r == 0)
                              break;
                  }
                  udev->descriptor.bMaxPacketSize0 =
                              buf->bMaxPacketSize0;
                  kfree(buf);

                  retval = hub_port_reset(hub, port1, udev, delay);
                  if (retval < 0)         /* error or disconnect */
                        goto fail;
                  if (oldspeed != udev->speed) {
                        dev_dbg(&udev->dev,
                              "device reset changed speed!\n");
                        retval = -ENODEV;
                        goto fail;
                  }
                  if (r) {
                        dev_err(&udev->dev, "device descriptor "
                                    "read/%s, error %d\n",
                                    "64", r);
                        retval = -EMSGSIZE;
                        continue;
                  }
#undef GET_DESCRIPTOR_BUFSIZE
            }

            for (j = 0; j < SET_ADDRESS_TRIES; ++j) {
                  retval = hub_set_address(udev);
                  if (retval >= 0)
                        break;
                  msleep(200);
            }
            if (retval < 0) {
                  dev_err(&udev->dev,
                        "device not accepting address %d, error %d\n",
                        udev->devnum, retval);
                  goto fail;
            }
 
            /* cope with hardware quirkiness:
             *  - let SET_ADDRESS settle, some device hardware wants it
             *  - read ep0 maxpacket even for high and low speed,
             */
            msleep(10);
            if (USE_NEW_SCHEME(retry_counter))
                  break;

            retval = usb_get_device_descriptor(udev, 8);
            if (retval < 8) {
                  dev_err(&udev->dev, "device descriptor "
                              "read/%s, error %d\n",
                              "8", retval);
                  if (retval >= 0)
                        retval = -EMSGSIZE;
            } else {
                  retval = 0;
                  break;
            }
      }
      if (retval)
            goto fail;

      i = udev->descriptor.bMaxPacketSize0;
      if (le16_to_cpu(udev->ep0.desc.wMaxPacketSize) != i) {
            if (udev->speed != USB_SPEED_FULL ||
                        !(i == 8 || i == 16 || i == 32 || i == 64)) {
                  dev_err(&udev->dev, "ep0 maxpacket = %d\n", i);
                  retval = -EMSGSIZE;
                  goto fail;
            }
            dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
            udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
            ep0_reinit(udev);
      }
  
      retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE);
      if (retval < (signed)sizeof(udev->descriptor)) {
            dev_err(&udev->dev, "device descriptor read/%s, error %d\n",
                  "all", retval);
            if (retval >= 0)
                  retval = -ENOMSG;
            goto fail;
      }

      retval = 0;

fail:
      if (retval)
            hub_port_disable(hub, port1, 0);
      mutex_unlock(&usb_address0_mutex);
      return retval;
}

static void
check_highspeed (struct usb_hub *hub, struct usb_device *udev, int port1)
{
      struct usb_qualifier_descriptor     *qual;
      int                     status;

      qual = kmalloc (sizeof *qual, SLAB_KERNEL);
      if (qual == NULL)
            return;

      status = usb_get_descriptor (udev, USB_DT_DEVICE_QUALIFIER, 0,
                  qual, sizeof *qual);
      if (status == sizeof *qual) {
            dev_info(&udev->dev, "not running at top speed; "
                  "connect to a high speed hub\n");
            /* hub LEDs are probably harder to miss than syslog */
            if (hub->has_indicators) {
                  hub->indicator[port1-1] = INDICATOR_GREEN_BLINK;
                  schedule_work (&hub->leds);
            }
      }
      kfree(qual);
}

static unsigned
hub_power_remaining (struct usb_hub *hub)
{
      struct usb_device *hdev = hub->hdev;
      int remaining;
      int port1;

      if (!hub->limited_power)
            return 0;

      remaining = hdev->bus_mA - hub->descriptor->bHubContrCurrent;
      for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
            struct usb_device *udev = hdev->children[port1 - 1];
            int               delta;

            if (!udev)
                  continue;

            /* Unconfigured devices may not use more than 100mA,
             * or 8mA for OTG ports */
            if (udev->actconfig)
                  delta = udev->actconfig->desc.bMaxPower * 2;
            else if (port1 != udev->bus->otg_port || hdev->parent)
                  delta = 100;
            else
                  delta = 8;
            if (delta > hub->mA_per_port)
                  dev_warn(&udev->dev, "%dmA is over %umA budget "
                              "for port %d!\n",
                              delta, hub->mA_per_port, port1);
            remaining -= delta;
      }
      if (remaining < 0) {
            dev_warn(hub->intfdev, "%dmA over power budget!\n",
                  - remaining);
            remaining = 0;
      }
      return remaining;
}

/* Handle physical or logical connection change events.
 * This routine is called when:
 *    a port connection-change occurs;
 *    a port enable-change occurs (often caused by EMI);
 *    usb_reset_device() encounters changed descriptors (as from
 *          a firmware download)
 * caller already locked the hub
 */
static void hub_port_connect_change(struct usb_hub *hub, int port1,
                              u16 portstatus, u16 portchange)
{
      struct usb_device *hdev = hub->hdev;
      struct device *hub_dev = hub->intfdev;
      u16 wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);
      int status, i;
 
      dev_dbg (hub_dev,
            "port %d, status %04x, change %04x, %s\n",
            port1, portstatus, portchange, portspeed (portstatus));

      if (hub->has_indicators) {
            set_port_led(hub, port1, HUB_LED_AUTO);
            hub->indicator[port1-1] = INDICATOR_AUTO;
      }
 
      /* Disconnect any existing devices under this port */
      if (hdev->children[port1-1])
            usb_disconnect(&hdev->children[port1-1]);
      clear_bit(port1, hub->change_bits);

#ifdef      CONFIG_USB_OTG
      /* during HNP, don't repeat the debounce */
      if (hdev->bus->is_b_host)
            portchange &= ~USB_PORT_STAT_C_CONNECTION;
#endif

      if (portchange & USB_PORT_STAT_C_CONNECTION) {
            status = hub_port_debounce(hub, port1);
            if (status < 0) {
                  dev_err (hub_dev,
                        "connect-debounce failed, port %d disabled\n",
                        port1);
                  goto done;
            }
            portstatus = status;
      }

      /* Return now if nothing is connected */
      if (!(portstatus & USB_PORT_STAT_CONNECTION)) {

            /* maybe switch power back on (e.g. root hub was reset) */
            if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2
                        && !(portstatus & (1 << USB_PORT_FEAT_POWER)))
                  set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
 
            if (portstatus & USB_PORT_STAT_ENABLE)
                  goto done;
            return;
      }

#ifdef  CONFIG_USB_SUSPEND
      /* If something is connected, but the port is suspended, wake it up. */
      if (portstatus & USB_PORT_STAT_SUSPEND) {
            status = hub_port_resume(hub, port1, NULL);
            if (status < 0) {
                  dev_dbg(hub_dev,
                        "can't clear suspend on port %d; %d\n",
                        port1, status);
                  goto done;
            }
      }
#endif

      for (i = 0; i < SET_CONFIG_TRIES; i++) {
            struct usb_device *udev;

            /* reallocate for each attempt, since references
             * to the previous one can escape in various ways
             */
            udev = usb_alloc_dev(hdev, hdev->bus, port1);
            if (!udev) {
                  dev_err (hub_dev,
                        "couldn't allocate port %d usb_device\n",
                        port1);
                  goto done;
            }

            usb_set_device_state(udev, USB_STATE_POWERED);
            udev->speed = USB_SPEED_UNKNOWN;
            udev->bus_mA = hub->mA_per_port;

            /* set the address */
            choose_address(udev);
            if (udev->devnum <= 0) {
                  status = -ENOTCONN;     /* Don't retry */
                  goto loop;
            }

            /* reset and get descriptor */
            status = hub_port_init(hub, udev, port1, i);
            if (status < 0)
                  goto loop;

            /* consecutive bus-powered hubs aren't reliable; they can
             * violate the voltage drop budget.  if the new child has
             * a "powered" LED, users should notice we didn't enable it
             * (without reading syslog), even without per-port LEDs
             * on the parent.
             */
            if (udev->descriptor.bDeviceClass == USB_CLASS_HUB
                        && udev->bus_mA <= 100) {
                  u16   devstat;

                  status = usb_get_status(udev, USB_RECIP_DEVICE, 0,
                              &devstat);
                  if (status < 2) {
                        dev_dbg(&udev->dev, "get status %d ?\n", status);
                        goto loop_disable;
                  }
                  le16_to_cpus(&devstat);
                  if ((devstat & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                        dev_err(&udev->dev,
                              "can't connect bus-powered hub "
                              "to this port\n");
                        if (hub->has_indicators) {
                              hub->indicator[port1-1] =
                                    INDICATOR_AMBER_BLINK;
                              schedule_work (&hub->leds);
                        }
                        status = -ENOTCONN;     /* Don't retry */
                        goto loop_disable;
                  }
            }
 
            /* check for devices running slower than they could */
            if (le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0200
                        && udev->speed == USB_SPEED_FULL
                        && highspeed_hubs != 0)
                  check_highspeed (hub, udev, port1);

            /* Store the parent's children[] pointer.  At this point
             * udev becomes globally accessible, although presumably
             * no one will look at it until hdev is unlocked.
             */
            status = 0;

            /* We mustn't add new devices if the parent hub has
             * been disconnected; we would race with the
             * recursively_mark_NOTATTACHED() routine.
             */
            spin_lock_irq(&device_state_lock);
            if (hdev->state == USB_STATE_NOTATTACHED)
                  status = -ENOTCONN;
            else
                  hdev->children[port1-1] = udev;
            spin_unlock_irq(&device_state_lock);

            /* Run it through the hoops (find a driver, etc) */
            if (!status) {
                  status = usb_new_device(udev);
                  if (status) {
                        spin_lock_irq(&device_state_lock);
                        hdev->children[port1-1] = NULL;
                        spin_unlock_irq(&device_state_lock);
                  }
            }

            if (status)
                  goto loop_disable;

            status = hub_power_remaining(hub);
            if (status)
                  dev_dbg(hub_dev, "%dmA power budget left\n", status);

            return;

loop_disable:
            hub_port_disable(hub, port1, 1);
loop:
            ep0_reinit(udev);
            release_address(udev);
            usb_put_dev(udev);
            if (status == -ENOTCONN)
                  break;
      }
 
done:
      hub_port_disable(hub, port1, 1);
}

static void hub_events(void)
{
      struct list_head *tmp;
      struct usb_device *hdev;
      struct usb_interface *intf;
      struct usb_hub *hub;
      struct device *hub_dev;
      u16 hubstatus;
      u16 hubchange;
      u16 portstatus;
      u16 portchange;
      int i, ret;
      int connect_change;

      /*
       *  We restart the list every time to avoid a deadlock with
       * deleting hubs downstream from this one. This should be
       * safe since we delete the hub from the event list.
       * Not the most efficient, but avoids deadlocks.
       */
      while (1) {

            /* Grab the first entry at the beginning of the list */
            spin_lock_irq(&hub_event_lock);
            if (list_empty(&hub_event_list)) {
                  spin_unlock_irq(&hub_event_lock);
                  break;
            }

            tmp = hub_event_list.next;
            list_del_init(tmp);

            hub = list_entry(tmp, struct usb_hub, event_list);
            hdev = hub->hdev;
            intf = to_usb_interface(hub->intfdev);
            hub_dev = &intf->dev;

            i = hub->resume_root_hub;

            dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x%s\n",
                        hdev->state, hub->descriptor
                              ? hub->descriptor->bNbrPorts
                              : 0,
                        /* NOTE: expects max 15 ports... */
                        (u16) hub->change_bits[0],
                        (u16) hub->event_bits[0],
                        i ? ", resume root" : "");

            usb_get_intf(intf);
            spin_unlock_irq(&hub_event_lock);

            /* Is this is a root hub wanting to reactivate the downstream
             * ports?  If so, be sure the interface resumes even if its
             * stub "device" node was never suspended.
             */
            if (i) {
                  dpm_runtime_resume(&hdev->dev);
                  dpm_runtime_resume(&intf->dev);
                  usb_put_intf(intf);
                  continue;
            }

            /* Lock the device, then check to see if we were
             * disconnected while waiting for the lock to succeed. */
            if (locktree(hdev) < 0) {
                  usb_put_intf(intf);
                  continue;
            }
            if (hub != usb_get_intfdata(intf))
                  goto loop;

            /* If the hub has died, clean up after it */
            if (hdev->state == USB_STATE_NOTATTACHED) {
                  hub->error = -ENODEV;
                  hub_pre_reset(intf);
                  goto loop;
            }

            /* If this is an inactive or suspended hub, do nothing */
            if (hub->quiescing)
                  goto loop;

            if (hub->error) {
                  dev_dbg (hub_dev, "resetting for error %d\n",
                        hub->error);

                  ret = usb_reset_composite_device(hdev, intf);
                  if (ret) {
                        dev_dbg (hub_dev,
                              "error resetting hub: %d\n", ret);
                        goto loop;
                  }

                  hub->nerrors = 0;
                  hub->error = 0;
            }

            /* deal with port status changes */
            for (i = 1; i <= hub->descriptor->bNbrPorts; i++) {
                  if (test_bit(i, hub->busy_bits))
                        continue;
                  connect_change = test_bit(i, hub->change_bits);
                  if (!test_and_clear_bit(i, hub->event_bits) &&
                              !connect_change && !hub->activating)
                        continue;

                  ret = hub_port_status(hub, i,
                              &portstatus, &portchange);
                  if (ret < 0)
                        continue;

                  if (hub->activating && !hdev->children[i-1] &&
                              (portstatus &
                                    USB_PORT_STAT_CONNECTION))
                        connect_change = 1;

                  if (portchange & USB_PORT_STAT_C_CONNECTION) {
                        clear_port_feature(hdev, i,
                              USB_PORT_FEAT_C_CONNECTION);
                        connect_change = 1;
                  }

                  if (portchange & USB_PORT_STAT_C_ENABLE) {
                        if (!connect_change)
                              dev_dbg (hub_dev,
                                    "port %d enable change, "
                                    "status %08x\n",
                                    i, portstatus);
                        clear_port_feature(hdev, i,
                              USB_PORT_FEAT_C_ENABLE);

                        /*
                         * EM interference sometimes causes badly
                         * shielded USB devices to be shutdown by
                         * the hub, this hack enables them again.
                         * Works at least with mouse driver. 
                         */
                        if (!(portstatus & USB_PORT_STAT_ENABLE)
                            && !connect_change
                            && hdev->children[i-1]) {
                              dev_err (hub_dev,
                                  "port %i "
                                  "disabled by hub (EMI?), "
                                  "re-enabling...\n",
                                    i);
                              connect_change = 1;
                        }
                  }

                  if (portchange & USB_PORT_STAT_C_SUSPEND) {
                        clear_port_feature(hdev, i,
                              USB_PORT_FEAT_C_SUSPEND);
                        if (hdev->children[i-1]) {
                              ret = remote_wakeup(hdev->
                                          children[i-1]);
                              if (ret < 0)
                                    connect_change = 1;
                        } else {
                              ret = -ENODEV;
                              hub_port_disable(hub, i, 1);
                        }
                        dev_dbg (hub_dev,
                              "resume on port %d, status %d\n",
                              i, ret);
                  }
                  
                  if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                        dev_err (hub_dev,
                              "over-current change on port %d\n",
                              i);
                        clear_port_feature(hdev, i,
                              USB_PORT_FEAT_C_OVER_CURRENT);
                        hub_power_on(hub);
                  }

                  if (portchange & USB_PORT_STAT_C_RESET) {
                        dev_dbg (hub_dev,
                              "reset change on port %d\n",
                              i);
                        clear_port_feature(hdev, i,
                              USB_PORT_FEAT_C_RESET);
                  }

                  if (connect_change)
                        hub_port_connect_change(hub, i,
                                    portstatus, portchange);
            } /* end for i */

            /* deal with hub status changes */
            if (test_and_clear_bit(0, hub->event_bits) == 0)
                  ;     /* do nothing */
            else if (hub_hub_status(hub, &hubstatus, &hubchange) < 0)
                  dev_err (hub_dev, "get_hub_status failed\n");
            else {
                  if (hubchange & HUB_CHANGE_LOCAL_POWER) {
                        dev_dbg (hub_dev, "power change\n");
                        clear_hub_feature(hdev, C_HUB_LOCAL_POWER);
                        if (hubstatus & HUB_STATUS_LOCAL_POWER)
                              /* FIXME: Is this always true? */
                              hub->limited_power = 0;
                        else
                              hub->limited_power = 1;
                  }
                  if (hubchange & HUB_CHANGE_OVERCURRENT) {
                        dev_dbg (hub_dev, "overcurrent change\n");
                        msleep(500);      /* Cool down */
                        clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
                              hub_power_on(hub);
                  }
            }

            hub->activating = 0;

            /* If this is a root hub, tell the HCD it's okay to
             * re-enable port-change interrupts now. */
            if (!hdev->parent)
                  usb_enable_root_hub_irq(hdev->bus);

loop:
            usb_unlock_device(hdev);
            usb_put_intf(intf);

        } /* end while (1) */
}

static int hub_thread(void *__unused)
{
      do {
            hub_events();
            wait_event_interruptible(khubd_wait,
                        !list_empty(&hub_event_list) ||
                        kthread_should_stop());
            try_to_freeze();
      } while (!kthread_should_stop() || !list_empty(&hub_event_list));

      pr_debug("%s: khubd exiting\n", usbcore_name);
      return 0;
}

static struct usb_device_id hub_id_table [] = {
    { .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
      .bDeviceClass = USB_CLASS_HUB},
    { .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS,
      .bInterfaceClass = USB_CLASS_HUB},
    { }                                   /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, hub_id_table);

static struct usb_driver hub_driver = {
      .name =           "hub",
      .probe =    hub_probe,
      .disconnect =     hub_disconnect,
      .suspend =  hub_suspend,
      .resume =   hub_resume,
      .pre_reset =      hub_pre_reset,
      .post_reset =     hub_post_reset,
      .ioctl =    hub_ioctl,
      .id_table = hub_id_table,
};

int usb_hub_init(void)
{
      if (usb_register(&hub_driver) < 0) {
            printk(KERN_ERR "%s: can't register hub driver\n",
                  usbcore_name);
            return -1;
      }

      khubd_task = kthread_run(hub_thread, NULL, "khubd");
      if (!IS_ERR(khubd_task))
            return 0;

      /* Fall through if kernel_thread failed */
      usb_deregister(&hub_driver);
      printk(KERN_ERR "%s: can't start khubd\n", usbcore_name);

      return -1;
}

void usb_hub_cleanup(void)
{
      kthread_stop(khubd_task);

      /*
       * Hub resources are freed for us by usb_deregister. It calls
       * usb_driver_purge on every device which in turn calls that
       * devices disconnect function if it is using this driver.
       * The hub_disconnect function takes care of releasing the
       * individual hub resources. -greg
       */
      usb_deregister(&hub_driver);
} /* usb_hub_cleanup() */

static int config_descriptors_changed(struct usb_device *udev)
{
      unsigned                index;
      unsigned                len = 0;
      struct usb_config_descriptor  *buf;

      for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
            if (len < le16_to_cpu(udev->config[index].desc.wTotalLength))
                  len = le16_to_cpu(udev->config[index].desc.wTotalLength);
      }
      buf = kmalloc (len, SLAB_KERNEL);
      if (buf == NULL) {
            dev_err(&udev->dev, "no mem to re-read configs after reset\n");
            /* assume the worst */
            return 1;
      }
      for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
            int length;
            int old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);

            length = usb_get_descriptor(udev, USB_DT_CONFIG, index, buf,
                        old_length);
            if (length < old_length) {
                  dev_dbg(&udev->dev, "config index %d, error %d\n",
                              index, length);
                  break;
            }
            if (memcmp (buf, udev->rawdescriptors[index], old_length)
                        != 0) {
                  dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
                        index, buf->bConfigurationValue);
                  break;
            }
      }
      kfree(buf);
      return index != udev->descriptor.bNumConfigurations;
}

/**
 * usb_reset_device - perform a USB port reset to reinitialize a device
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * WARNING - don't use this routine to reset a composite device
 * (one with multiple interfaces owned by separate drivers)!
 * Use usb_reset_composite_device() instead.
 *
 * Do a port reset, reassign the device's address, and establish its
 * former operating configuration.  If the reset fails, or the device's
 * descriptors change from their values before the reset, or the original
 * configuration and altsettings cannot be restored, a flag will be set
 * telling khubd to pretend the device has been disconnected and then
 * re-connected.  All drivers will be unbound, and the device will be
 * re-enumerated and probed all over again.
 *
 * Returns 0 if the reset succeeded, -ENODEV if the device has been
 * flagged for logical disconnection, or some other negative error code
 * if the reset wasn't even attempted.
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 */
int usb_reset_device(struct usb_device *udev)
{
      struct usb_device       *parent_hdev = udev->parent;
      struct usb_hub                *parent_hub;
      struct usb_device_descriptor  descriptor = udev->descriptor;
      int                     i, ret = 0;
      int                     port1 = udev->portnum;

      if (udev->state == USB_STATE_NOTATTACHED ||
                  udev->state == USB_STATE_SUSPENDED) {
            dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                        udev->state);
            return -EINVAL;
      }

      if (!parent_hdev) {
            /* this requires hcd-specific logic; see OHCI hc_restart() */
            dev_dbg(&udev->dev, "%s for root hub!\n", __FUNCTION__);
            return -EISDIR;
      }
      parent_hub = hdev_to_hub(parent_hdev);

      set_bit(port1, parent_hub->busy_bits);
      for (i = 0; i < SET_CONFIG_TRIES; ++i) {

            /* ep0 maxpacket size may change; let the HCD know about it.
             * Other endpoints will be handled by re-enumeration. */
            ep0_reinit(udev);
            ret = hub_port_init(parent_hub, udev, port1, i);
            if (ret >= 0)
                  break;
      }
      clear_bit(port1, parent_hub->busy_bits);
      if (ret < 0)
            goto re_enumerate;
 
      /* Device might have changed firmware (DFU or similar) */
      if (memcmp(&udev->descriptor, &descriptor, sizeof descriptor)
                  || config_descriptors_changed (udev)) {
            dev_info(&udev->dev, "device firmware changed\n");
            udev->descriptor = descriptor;      /* for disconnect() calls */
            goto re_enumerate;
      }
  
      if (!udev->actconfig)
            goto done;

      ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                  USB_REQ_SET_CONFIGURATION, 0,
                  udev->actconfig->desc.bConfigurationValue, 0,
                  NULL, 0, USB_CTRL_SET_TIMEOUT);
      if (ret < 0) {
            dev_err(&udev->dev,
                  "can't restore configuration #%d (error=%d)\n",
                  udev->actconfig->desc.bConfigurationValue, ret);
            goto re_enumerate;
      }
      usb_set_device_state(udev, USB_STATE_CONFIGURED);

      for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
            struct usb_interface *intf = udev->actconfig->interface[i];
            struct usb_interface_descriptor *desc;

            /* set_interface resets host side toggle even
             * for altsetting zero.  the interface may have no driver.
             */
            desc = &intf->cur_altsetting->desc;
            ret = usb_set_interface(udev, desc->bInterfaceNumber,
                  desc->bAlternateSetting);
            if (ret < 0) {
                  dev_err(&udev->dev, "failed to restore interface %d "
                        "altsetting %d (error=%d)\n",
                        desc->bInterfaceNumber,
                        desc->bAlternateSetting,
                        ret);
                  goto re_enumerate;
            }
      }

done:
      return 0;
 
re_enumerate:
      hub_port_logical_disconnect(parent_hub, port1);
      return -ENODEV;
}

/**
 * usb_reset_composite_device - warn interface drivers and perform a USB port reset
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 * @iface: interface bound to the driver making the request (optional)
 *
 * Warns all drivers bound to registered interfaces (using their pre_reset
 * method), performs the port reset, and then lets the drivers know that
 * the reset is over (using their post_reset method).
 *
 * Return value is the same as for usb_reset_device().
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 *
 * The interface locks are acquired during the pre_reset stage and released
 * during the post_reset stage.  However if iface is not NULL and is
 * currently being probed, we assume that the caller already owns its
 * lock.
 */
int usb_reset_composite_device(struct usb_device *udev,
            struct usb_interface *iface)
{
      int ret;
      struct usb_host_config *config = udev->actconfig;

      if (udev->state == USB_STATE_NOTATTACHED ||
                  udev->state == USB_STATE_SUSPENDED) {
            dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                        udev->state);
            return -EINVAL;
      }

      if (iface && iface->condition != USB_INTERFACE_BINDING)
            iface = NULL;

      if (config) {
            int i;
            struct usb_interface *cintf;
            struct usb_driver *drv;

            for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                  cintf = config->interface[i];
                  if (cintf != iface)
                        down(&cintf->dev.sem);
                  if (device_is_registered(&cintf->dev) &&
                              cintf->dev.driver) {
                        drv = to_usb_driver(cintf->dev.driver);
                        if (drv->pre_reset)
                              (drv->pre_reset)(cintf);
                  }
            }
      }

      ret = usb_reset_device(udev);

      if (config) {
            int i;
            struct usb_interface *cintf;
            struct usb_driver *drv;

            for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
                  cintf = config->interface[i];
                  if (device_is_registered(&cintf->dev) &&
                              cintf->dev.driver) {
                        drv = to_usb_driver(cintf->dev.driver);
                        if (drv->post_reset)
                              (drv->post_reset)(cintf);
                  }
                  if (cintf != iface)
                        up(&cintf->dev.sem);
            }
      }

      return ret;
}

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